textproduct: Quad Cities

KEY MESSAGES

- A pattern change this weekend will bring heat and high humidity to the area and persist into next week. The probability of heat headlines continues to increase (50-70% chance).

SHORT TERM /THROUGH FRIDAY/

Issued at 145 AM CDT Thu Jun 25 2026

A dry Thursday ahead as the cold front clears the area by sunrise and dew points fall a few degrees, making today comparable to Tuesday. Scattered low level clouds will develop as surface troughing lingers across eastern Iowa and northwest Illinois. Our attention shifts to the next mid-level shortwave ejecting into the Central Plains though. Surface cyclogenesis is forecasted to occur over northern Texas as the cold front from Wednesday stalls out across central Missouri and some cirrus start to intrude into the southern CWA.

Heading into Thursday night, our light winds are expected to shift slowly from northwesterly to easterly as the low pressure over the Southern Plains moves into southern Kansas, essentially along the stationary front. Lows drop back into the upper 50s to mid 60s, but cloud cover could hamper radiational cooling, especially south of Interstate 80. Light showers may also start to develop south of Highway 34 along a mid-level F-gen band and isentropic upglide in the low levels. The magnitude of dry air advection during the day on Thursday will determine if the onset of precipitation is delayed to Friday morning.

By Friday, the low pressure propagates into north-central Missouri, converting the stationary front into warm front inching northward. The mid-level trough supporting this system also moves into northern Missouri, but the lack of curvature in the flow limits the 500 mb vorticity to purely shear-driven. This is good news for most of the CWA north of Interstate 80 as the main source of lift being displaced so far to the south means they will likely (80-90%) have a dry Friday while areas south will have stratiform rainfall similar to Sunday. The 24.18z REFS run has accumulations relatively light along and south of Interstate 80 with a 20-40% chance of greater than a quarter of an inch south of Highway 34. Therefore, the threat of excessive rainfall with this system is low.

LONG TERM /FRIDAY NIGHT THROUGH WEDNESDAY/

Issued at 145 AM CDT Thu Jun 25 2026

Friday Night-Sunday...Conditions dry out heading into Friday night as the low pressure over Missouri weakens significantly from the lack of mid-to-upper-level dynamical support and the warm front once again converts to a stationary front. A Great Lakes high pressure is expected to keep winds easterly north of this stationary boundary with some lingering showers possible into Saturday. Our attention once again shifts out west where a seasonably strong low heights center will dig into the western CONUS, enabling a longwave ridge to build ahead of it across the Great Plains. This kicks off a warming and moistening trend Saturday night when pressure falls along the Central and Northern Rockies turn the low-level flow out of the south, forcing the stationary front to transition into a warm front (again!) and move northward into our CWA. Isolated (20-40%) PoPs are currently forecasted along this boundary Saturday night into Sunday morning. In terms of severe weather, that remains uncertain. The 24.12z LREF run has a 60-80% joint probability of MUCAPE values exceeding 500 J/kg and sfc-to-500 mb bulk shear exceeding 30 knots along the front, but with ridging building overhead, convective initiation should struggle to occur. Once the warm front clears the area from south to north, dew points soar into the mid-to-upper 70s (60-80% chance per the 24.12z LREF run), setting the stage for potential excessive heat early next week.

Monday-Wednesday...With the warm sector fully in place, Monday appears to the day with the greatest chance at seeing heat headlines with the 24.12z LREF run having a 50-70% chance (10% higher compared to yesterday) of heat indices exceeding 100 degrees. By Tuesday, a shortwave embedded in the longwave trough, now over the Rockies, lifts northward into central Canada, reorienting the ridge over much of the eastern CONUS and introducing southwesterly flow aloft over Iowa. This will open the door for subtle shortwave passages and increasing PoPs slightly Tuesday night and Wednesday. The weakening of the northwestern edge of the heat dome could provide a couple degrees of relief, but heat headlines remain possible (40-60%).

AVIATION /12Z TAFS THROUGH 12Z FRIDAY/

Issued at 620 AM CDT Thu Jun 25 2026

Aside from some patchy shallow MVFR/IFR fog at CID and BRL early this morning, VFR will prevail into tonight with an area of high pressure remaining anchored over the Great Lakes region. Rain chances will increase at BRL late tonight as the next storm system approaches from the southwest, which could result in a period of MVFR ceilings and visibilities.

DVN WATCHES/WARNINGS/ADVISORIES

IA...None. IL...None. MO...None.